Many variations of human powered vehicles attempt to independently combine arm and leg power. This is an advantage for transportation purposes and also produces better overall exercise than is possible with pedal-crank bicycles. The rowing motion is the most natural form for coordinating arm and leg power, but has never been successfuly incorporated into a genuinely practical land vehicle.
U.S. Pat. No. 4,632,414 discloses a three-wheeled land vehicle that does a good job of simulating rowing. The same may be said for the vehicles disclosed in U.S. Pat. Nos. 4,700,962 and 4,796,907. The vehicle of U.S. Pat. No. 4,305,600 uses rowing motion on a simpler two-wheeled vehicle. Unfortunately, for all of these vehicles, the arm and leg forces are not truly additive. All of the power delivered to the drive wheel must be transferred through the arms, which fatigue quickly.
U.S. Pat. Nos. 4,928,986 and 4,508,358 disclose vehicles that are two wheelers in at least one embodiment and use arm and leg power independently. Unfortunately, they are encumbered by heavy, inefficient mechanisms resulting from essentially separate drive systems for the arms and legs.
All vehicles that have attempted to combine arm and leg power have proved too awkward in handling, and too inefficient due to weight and complexity or poor conservation of kinetic energy. Most are also hindered by poor impedance matching between the operator and machine through less than optimum leverage, stroke amplitude, or gearing.
It is well known that rowing is one of the best motions for exercising all the major muscle groups. It is less well known that this motion can produce more horsepower than that of turning a pedal crank; thereby, making the human body a more powerful engine for driving a vehicle. What has never before been created is a vehicle that can utilize this motion in a light weight, energy efficient system, while at the same time providing a comfortable body position and easy handling for an overall superior Human Powered Vehicle.